1. Field of the Invention
The present invention concerns a sound insulating device for reducing propagation of vibrational impact sounds. More in particular, it relates to a sound insulating device suitable to use as a sound insulating floor device for reducing impact sounds generated in upstairs from transmitting to adjacent downstairs of a house.
2. Description of the Prior Art
In recent years, floor impact sounds from upstairs of a house have caused a significant problem, for example, in apartment houses. The floor impact sounds include floor impact sounds caused by light weight impact shocks which are generated upon ordinary walking and floor impact sounds caused by heavy weight impact shocks which are generated upon falling of a heavy weight mass or upon leaping action of a children or the like, and there was no effective countermeasure other than increasing the thickness of floor slabs, particularly, for floor impact sounds caused by heavy weight impact shocks.
However, if the thickness of the floor slabs is increased, the number of stories that can be constructed within a predetermined designed height is decreased and the cost for the construction materials is also increased. Accordingly, this can not always be considered as an effective means. Further, this method is extremely difficult to be applied to a wooden residence.
In view of the above, the present applicant has previously proposed a sound insulating device having a shock absorbing mechanism of a reduced vertical size to be put between an upper material and a lower material which can be applied easily also to existent buildings or timber houses and which is free from a worry of worsening the habitability as shown in Japanese Patent Laid-Open Hel 2-289759.
In this sound insulating device proposed previously by the present applicant, since the vibrational impact sounds are absorbed by an elastic member and the elastic recovery of the elastic member is resisted by a damping mechanism, it has a merit capable of absorbing heavy weight impact sounds without deteriorating the habitability. However, if it is intended to absorb also the light weight impact sounds by this shock absorbing mechanism, it results in a problem of worsening the habitability or reducing the absorbing effect for heavy weight impact sounds.